interface.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  * Copyright (C) 2014 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #define _GNU_SOURCE
  16 #include <sys/socket.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <sys/utsname.h>
  21 #include <net/if.h>
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30
  31 #include <libubox/usock.h>
  32 #include <libubox/uloop.h>
  33 #include <libubox/avl-cmp.h>
  34 #include <libubox/utils.h>
  35 #include "interface.h"
  36 #include "util.h"
  37 #include "dns.h"
  38 #include "announce.h"
  39
  40 static int
  41 interface_send_packet4(struct interface *iface, struct iovec *iov, int iov_len)
  42 {
  43         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
  44         static struct sockaddr_in a;
  45         static struct msghdr m = {
  46                 .msg_name = (struct sockaddr *) &a,
  47                 .msg_namelen = sizeof(a),
  48                 .msg_control = cmsg_data,
  49                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  50         };
  51         struct in_pktinfo *pkti;
  52         struct cmsghdr *cmsg;
  53         int fd = iface->fd.fd;
  54
  55         a.sin_family = AF_INET;
  56         a.sin_port = htons(MCAST_PORT);
  57         m.msg_iov = iov;
  58         m.msg_iovlen = iov_len;
  59
  60         memset(cmsg_data, 0, sizeof(cmsg_data));
  61         cmsg = CMSG_FIRSTHDR(&m);
  62         cmsg->cmsg_len = m.msg_controllen;
  63         cmsg->cmsg_level = IPPROTO_IP;
  64         cmsg->cmsg_type = IP_PKTINFO;
  65
  66         pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
  67         pkti->ipi_ifindex = iface->ifindex;
  68
  69         a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
  70
  71         return sendmsg(fd, &m, 0);
  72 }
  73
  74 static int
  75 interface_send_packet6(struct interface *iface, struct iovec *iov, int iov_len)
  76 {
  77         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in6_pktinfo)) / sizeof(size_t)) + 1];
  78         static struct sockaddr_in6 a;
  79         static struct msghdr m = {
  80                 .msg_name = (struct sockaddr *) &a,
  81                 .msg_namelen = sizeof(a),
  82                 .msg_control = cmsg_data,
  83                 .msg_controllen = CMSG_LEN(sizeof(struct in6_pktinfo)),
  84         };
  85         struct in6_pktinfo *pkti;
  86         struct cmsghdr *cmsg;
  87         int fd = iface->fd.fd;
  88
  89         a.sin6_family = AF_INET6;
  90         a.sin6_port = htons(MCAST_PORT);
  91         m.msg_iov = iov;
  92         m.msg_iovlen = iov_len;
  93
  94         memset(cmsg_data, 0, sizeof(cmsg_data));
  95         cmsg = CMSG_FIRSTHDR(&m);
  96         cmsg->cmsg_len = m.msg_controllen;
  97         cmsg->cmsg_level = IPPROTO_IPV6;
  98         cmsg->cmsg_type = IPV6_PKTINFO;
  99
 100         pkti = (struct in6_pktinfo*) CMSG_DATA(cmsg);
 101         pkti->ipi6_ifindex = iface->ifindex;
 102
 103         inet_pton(AF_INET6, MCAST_ADDR6, &a.sin6_addr);
 104
 105         return sendmsg(fd, &m, 0);
 106 }
 107
 108 int
 109 interface_send_packet(struct interface *iface, struct iovec *iov, int iov_len)
 110 {
 111         if (iface->v6)
 112                 return interface_send_packet6(iface, iov, iov_len);
 113
 114         return interface_send_packet4(iface, iov, iov_len);
 115 }
 116
 117 static void interface_close(struct interface *iface)
 118 {
 119         if (iface->fd.fd < 0)
 120                 return;
 121
 122         announce_free(iface);
 123         uloop_fd_delete(&iface->fd);
 124         close(iface->fd.fd);
 125         iface->fd.fd = -1;
 126 }
 127
 128 static void interface_free(struct interface *iface)
 129 {
 130         interface_close(iface);
 131         free(iface);
 132 }
 133
 134 static void
 135 read_socket(struct uloop_fd *u, unsigned int events)
 136 {
 137         struct interface *iface = container_of(u, struct interface, fd);
 138         static uint8_t buffer[8 * 1024];
 139         int len;
 140
 141         if (u->eof) {
 142                 interface_close(iface);
 143                 uloop_timeout_set(&iface->reconnect, 1000);
 144                 return;
 145         }
 146
 147         len = read(u->fd, buffer, sizeof(buffer));
 148         if (len < 1) {
 149                 if (errno != EAGAIN)
 150                         fprintf(stderr, "read failed: %s\n", strerror(errno));
 151                 return;
 152         }
 153
 154         dns_handle_packet(iface, buffer, len);
 155 }
 156
 157 static int
 158 interface_socket_setup4(struct interface *iface)
 159 {
 160         struct ip_mreqn mreq;
 161         uint8_t ttl = 255;
 162         int yes = 1;
 163         int no = 0;
 164         struct sockaddr_in sa = { 0 };
 165         int fd = iface->fd.fd;
 166
 167         sa.sin_family = AF_INET;
 168         sa.sin_port = htons(MCAST_PORT);
 169         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 170
 171         memset(&mreq, 0, sizeof(mreq));
 172         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 173         mreq.imr_multiaddr = sa.sin_addr;
 174         mreq.imr_ifindex = iface->ifindex;
 175
 176         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 177                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 178
 179         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 180                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 181
 182         /* Some network drivers have issues with dropping membership of
 183          * mcast groups when the iface is down, but don't allow rejoining
 184          * when it comes back up. This is an ugly workaround
 185          * -- this was copied from avahi --
 186          */
 187         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 188
 189         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 190                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 191                 close(fd);
 192                 fd = -1;
 193                 return -1;
 194         }
 195
 196         if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 197                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 198
 199         if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 200                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 201
 202         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 203                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 204
 205         return 0;
 206 }
 207
 208 static int
 209 interface_socket_setup6(struct interface *iface)
 210 {
 211         struct ipv6_mreq mreq;
 212         int ttl = 255;
 213         int yes = 1;
 214         int no = 0;
 215         struct sockaddr_in6 sa = { 0 };
 216         int fd = iface->fd.fd;
 217
 218         sa.sin6_family = AF_INET6;
 219         sa.sin6_port = htons(MCAST_PORT);
 220         inet_pton(AF_INET6, MCAST_ADDR6, &sa.sin6_addr);
 221
 222         memset(&mreq, 0, sizeof(mreq));
 223         mreq.ipv6mr_multiaddr = sa.sin6_addr;
 224         mreq.ipv6mr_interface = iface->ifindex;
 225
 226         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 227                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_HOPS\n");
 228
 229         if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 230                 fprintf(stderr, "ioctl failed: IPV6_UNICAST_HOPS\n");
 231
 232         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 233                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 234
 235         setsockopt(fd, IPPROTO_IPV6, IPV6_LEAVE_GROUP, &mreq, sizeof(mreq));
 236         if (setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 237                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 238                 close(fd);
 239                 fd = -1;
 240                 return -1;
 241         }
 242
 243         if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0)
 244                 fprintf(stderr, "ioctl failed: IPV6_RECVPKTINFO\n");
 245
 246         if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0)
 247                 fprintf(stderr, "ioctl failed: IPV6_RECVHOPLIMIT\n");
 248
 249         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 250                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_LOOP\n");
 251
 252         return 0;
 253 }
 254
 255 static void
 256 reconnect_socket(struct uloop_timeout *timeout)
 257 {
 258         struct interface *iface = container_of(timeout, struct interface, reconnect);
 259         char mcast_addr[16];
 260         int type = 0;
 261
 262         if (iface->v6) {
 263                 snprintf(mcast_addr, sizeof(mcast_addr), "%s%%%s", iface->mcast_addr, iface->name);
 264                 type = USOCK_IPV6ONLY;
 265         } else {
 266                 snprintf(mcast_addr, sizeof(mcast_addr), "%s", iface->mcast_addr);
 267                 type = USOCK_IPV4ONLY;
 268         }
 269
 270         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | type, mcast_addr, "5353");
 271         if (iface->fd.fd < 0) {
 272                 fprintf(stderr, "failed to add listener %s: %s\n", mcast_addr, strerror(errno));
 273                 goto retry;
 274         }
 275
 276         if (!iface->v6 && interface_socket_setup4(iface)) {
 277                 iface->fd.fd = -1;
 278                 goto retry;
 279         }
 280
 281         if (iface->v6 && interface_socket_setup6(iface)) {
 282                 iface->fd.fd = -1;
 283                 goto retry;
 284         }
 285
 286         uloop_fd_add(&iface->fd, ULOOP_READ);
 287         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 288         announce_init(iface);
 289         return;
 290
 291 retry:
 292         uloop_timeout_set(timeout, 1000);
 293 }
 294
 295
 296 static void interface_start(struct interface *iface)
 297 {
 298         iface->fd.cb = read_socket;
 299         iface->reconnect.cb = reconnect_socket;
 300         uloop_timeout_set(&iface->reconnect, 100);
 301 }
 302
 303 static void
 304 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 305                 struct vlist_node *node_old)
 306 {
 307         struct interface *iface;
 308
 309         if (node_old) {
 310                 iface = container_of(node_old, struct interface, node);
 311                 interface_free(iface);
 312         }
 313
 314         if (node_new) {
 315                 iface = container_of(node_new, struct interface, node);
 316                 interface_start(iface);
 317         }
 318 }
 319
 320 static int
 321 get_iface_ipv4(struct interface *iface)
 322 {
 323         struct sockaddr_in *sin;
 324         struct ifreq ir;
 325         int sock, ret = -1;
 326
 327         sock = socket(AF_INET, SOCK_DGRAM, 0);
 328         if (sock < 0)
 329                 return -1;
 330
 331         memset(&ir, 0, sizeof(struct ifreq));
 332         strncpy(ir.ifr_name, iface->name, sizeof(ir.ifr_name));
 333
 334         ret = ioctl(sock, SIOCGIFADDR, &ir);
 335         if (ret < 0)
 336                 goto out;
 337
 338         sin = (struct sockaddr_in *) &ir.ifr_addr;
 339         memcpy(&iface->v4_addr, &sin->sin_addr, sizeof(iface->v4_addr));
 340         iface->mcast_addr = MCAST_ADDR;
 341 out:
 342         close(sock);
 343         return ret;
 344 }
 345
 346 static int
 347 get_iface_ipv6(struct interface *iface)
 348 {
 349         struct sockaddr_in6 addr = {AF_INET6, 0, iface->ifindex, IN6ADDR_ANY_INIT, 0};
 350         socklen_t alen = sizeof(addr);
 351         int sock, ret = -1;
 352
 353         addr.sin6_addr.s6_addr[0] = 0xff;
 354         addr.sin6_addr.s6_addr[1] = 0x02;
 355         addr.sin6_addr.s6_addr[15] = 0x01;
 356
 357         sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
 358         connect(sock, (struct sockaddr*)&addr, sizeof(addr));
 359         ret = getsockname(sock, (struct sockaddr*)&addr, &alen);
 360         if (!ret) {
 361                 memcpy(&iface->v6_addr, &addr.sin6_addr, sizeof(iface->v6_addr));
 362                 iface->mcast_addr = MCAST_ADDR6;
 363                 iface->v6 = 1;
 364         }
 365         close(sock);
 366         return ret;
 367 }
 368
 369 static int _interface_add(const char *name, int v6)
 370 {
 371         struct interface *iface;
 372         char *name_buf;
 373         char *id_buf;
 374
 375         iface = calloc_a(sizeof(*iface),
 376                 &name_buf, strlen(name) + 1,
 377                 &id_buf, strlen(name) + 3);
 378
 379         sprintf(id_buf, "%d_%s", v6, name);
 380         iface->name = strcpy(name_buf, name);
 381         iface->id = id_buf;
 382         iface->ifindex = if_nametoindex(name);
 383         iface->fd.fd = -1;
 384
 385         if (iface->ifindex <= 0)
 386                 goto error;
 387
 388         if (!v6 && get_iface_ipv4(iface))
 389                 goto error;
 390
 391         if (v6 && get_iface_ipv6(iface))
 392                 goto error;
 393
 394         vlist_add(&interfaces, &iface->node, iface->id);
 395         return 0;
 396
 397 error:
 398         free(iface);
 399         return -1;
 400 }
 401
 402 int interface_add(const char *name)
 403 {
 404         int v4 = _interface_add(name, 0);
 405         int v6 = _interface_add(name, 1);
 406         return v4 && v6;
 407 }
 408
 409 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);